add kern.bufcachepercent sysctl to allow adjusting the buffer cache

size on a running system.
ok art@, oga@

21 files changed, 70 insertions, 123 deletions

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index d8492b681a0..f3f42876d2f 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.92 2009/06/02 03:04:54 jordan Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.93 2009/06/03 21:30:19 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.3 2003/05/07 22:58:18 fvdl Exp $	*/
 
 /*-
@@ -399,12 +399,6 @@ setup_buffers()
 	 */
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
-
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
 }
 
 /*
diff --git a/sys/arch/aviion/aviion/machdep.c b/sys/arch/aviion/aviion/machdep.c
index f7f5f12df18..3b8237656c5 100644
--- a/sys/arch/aviion/aviion/machdep.c
+++ b/sys/arch/aviion/aviion/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.27 2009/04/19 17:56:12 miod Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.28 2009/06/03 21:30:19 beck Exp $	*/
 /*
  * Copyright (c) 2007 Miodrag Vallat.
  *
@@ -293,12 +293,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/hp300/hp300/machdep.c b/sys/arch/hp300/hp300/machdep.c
index ed2c256b29c..d560a1b7c58 100644
--- a/sys/arch/hp300/hp300/machdep.c
+++ b/sys/arch/hp300/hp300/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.120 2008/06/27 17:22:14 miod Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.121 2009/06/03 21:30:19 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.121 1999/03/26 23:41:29 mycroft Exp $	*/
 
 /*
@@ -290,12 +290,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/hppa/hppa/machdep.c b/sys/arch/hppa/hppa/machdep.c
index 58188d3c89d..f7c0af3f823 100644
--- a/sys/arch/hppa/hppa/machdep.c
+++ b/sys/arch/hppa/hppa/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.171 2009/02/14 18:51:03 kettenis Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.172 2009/06/03 21:30:19 beck Exp $	*/
 
 /*
  * Copyright (c) 1999-2003 Michael Shalayeff
@@ -653,12 +653,6 @@ cpu_startup(void)
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/hppa64/hppa64/machdep.c b/sys/arch/hppa64/hppa64/machdep.c
index 3794891ae17..e3385e60162 100644
--- a/sys/arch/hppa64/hppa64/machdep.c
+++ b/sys/arch/hppa64/hppa64/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.13 2009/02/04 17:19:17 miod Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.14 2009/06/03 21:30:19 beck Exp $	*/
 
 /*
  * Copyright (c) 2005 Michael Shalayeff
@@ -406,12 +406,6 @@ cpu_startup(void)
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 printf("here3\n");
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
diff --git a/sys/arch/i386/i386/machdep.c b/sys/arch/i386/i386/machdep.c
index b255c2bf145..ad3a266aa0f 100644
--- a/sys/arch/i386/i386/machdep.c
+++ b/sys/arch/i386/i386/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.451 2009/06/03 00:41:48 weingart Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.452 2009/06/03 21:30:19 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.214 1996/11/10 03:16:17 thorpej Exp $	*/
 
 /*-
@@ -547,11 +547,6 @@ setup_buffers()
 	if (bufpages == 0)
 		bufpages = atop(avail_end) * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4)
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
 }
 
 /*
diff --git a/sys/arch/luna88k/luna88k/machdep.c b/sys/arch/luna88k/luna88k/machdep.c
index 79be85bbecc..27a6f7ae066 100644
--- a/sys/arch/luna88k/luna88k/machdep.c
+++ b/sys/arch/luna88k/luna88k/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.62 2009/04/19 17:56:13 miod Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.63 2009/06/03 21:30:19 beck Exp $	*/
 /*
  * Copyright (c) 1998, 1999, 2000, 2001 Steve Murphree, Jr.
  * Copyright (c) 1996 Nivas Madhur
@@ -470,12 +470,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/mac68k/mac68k/machdep.c b/sys/arch/mac68k/mac68k/machdep.c
index 3eb2c4d2ea9..a86c163e416 100644
--- a/sys/arch/mac68k/mac68k/machdep.c
+++ b/sys/arch/mac68k/mac68k/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.147 2008/11/09 12:34:47 tobias Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.148 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.207 1998/07/08 04:39:34 thorpej Exp $	*/
 
 /*
@@ -419,12 +419,6 @@ cpu_startup(void)
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/macppc/macppc/machdep.c b/sys/arch/macppc/macppc/machdep.c
index bf30d430a40..b337075e78e 100644
--- a/sys/arch/macppc/macppc/machdep.c
+++ b/sys/arch/macppc/macppc/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.105 2009/06/02 21:38:09 drahn Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.106 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.4 1996/10/16 19:33:11 ws Exp $	*/
 
 /*
@@ -509,12 +509,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/mvme68k/mvme68k/machdep.c b/sys/arch/mvme68k/mvme68k/machdep.c
index 206d606a0da..836bec8ec95 100644
--- a/sys/arch/mvme68k/mvme68k/machdep.c
+++ b/sys/arch/mvme68k/mvme68k/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.114 2009/03/15 20:40:25 miod Exp $ */
+/*	$OpenBSD: machdep.c,v 1.115 2009/06/03 21:30:20 beck Exp $ */
 
 /*
  * Copyright (c) 1995 Theo de Raadt
@@ -265,12 +265,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/mvme88k/mvme88k/machdep.c b/sys/arch/mvme88k/mvme88k/machdep.c
index ef4828c388a..32c28247423 100644
--- a/sys/arch/mvme88k/mvme88k/machdep.c
+++ b/sys/arch/mvme88k/mvme88k/machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: machdep.c,v 1.229 2009/04/19 17:56:13 miod Exp $	*/
+/* $OpenBSD: machdep.c,v 1.230 2009/06/03 21:30:20 beck Exp $	*/
 /*
  * Copyright (c) 1998, 1999, 2000, 2001 Steve Murphree, Jr.
  * Copyright (c) 1996 Nivas Madhur
@@ -404,12 +404,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/mvmeppc/mvmeppc/machdep.c b/sys/arch/mvmeppc/mvmeppc/machdep.c
index ba2f1a3ae1d..42da01b655a 100644
--- a/sys/arch/mvmeppc/mvmeppc/machdep.c
+++ b/sys/arch/mvmeppc/mvmeppc/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.56 2008/04/09 16:58:10 deraadt Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.57 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.4 1996/10/16 19:33:11 ws Exp $	*/
 
 /*
@@ -415,12 +415,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/sgi/sgi/machdep.c b/sys/arch/sgi/sgi/machdep.c
index db730e18e6d..79a4121064d 100644
--- a/sys/arch/sgi/sgi/machdep.c
+++ b/sys/arch/sgi/sgi/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.70 2009/05/28 18:03:55 miod Exp $ */
+/*	$OpenBSD: machdep.c,v 1.71 2009/06/03 21:30:20 beck Exp $ */
 
 /*
  * Copyright (c) 2003-2004 Opsycon AB  (www.opsycon.se / www.opsycon.com)
@@ -771,12 +771,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm. */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments. This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/socppc/socppc/machdep.c b/sys/arch/socppc/socppc/machdep.c
index 1743306806d..e9b77c46f97 100644
--- a/sys/arch/socppc/socppc/machdep.c
+++ b/sys/arch/socppc/socppc/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.10 2009/06/02 21:38:10 drahn Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.11 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.4 1996/10/16 19:33:11 ws Exp $	*/
 
 /*
@@ -772,12 +772,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/solbourne/solbourne/machdep.c b/sys/arch/solbourne/solbourne/machdep.c
index 5e240c0c371..cc3e64cf9a7 100644
--- a/sys/arch/solbourne/solbourne/machdep.c
+++ b/sys/arch/solbourne/solbourne/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.8 2009/02/04 17:19:17 miod Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.9 2009/06/03 21:30:20 beck Exp $	*/
 /*	OpenBSD: machdep.c,v 1.105 2005/04/11 15:13:01 deraadt Exp 	*/
 
 /*
@@ -190,12 +190,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/sparc/sparc/machdep.c b/sys/arch/sparc/sparc/machdep.c
index a0dfdd414c1..ea63610774f 100644
--- a/sys/arch/sparc/sparc/machdep.c
+++ b/sys/arch/sparc/sparc/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.116 2008/06/27 17:22:15 miod Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.117 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: machdep.c,v 1.85 1997/09/12 08:55:02 pk Exp $ */
 
 /*
@@ -203,12 +203,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively
 	 * limits the number of processes exec'ing at any time.
diff --git a/sys/arch/vax/vax/machdep.c b/sys/arch/vax/vax/machdep.c
index 1eaa5fb3ac9..fd9433bcbba 100644
--- a/sys/arch/vax/vax/machdep.c
+++ b/sys/arch/vax/vax/machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: machdep.c,v 1.99 2008/08/18 23:19:29 miod Exp $ */
+/* $OpenBSD: machdep.c,v 1.100 2009/06/03 21:30:20 beck Exp $ */
 /* $NetBSD: machdep.c,v 1.108 2000/09/13 15:00:23 thorpej Exp $	 */
 
 /*
@@ -212,12 +212,6 @@ cpu_startup()
 	if (bufpages == 0)
 		bufpages = physmem * bufcachepercent / 100;
 
-	/* Restrict to at most 25% filled kvm */
-	if (bufpages >
-	    (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) / PAGE_SIZE / 4) 
-		bufpages = (VM_MAX_KERNEL_ADDRESS-VM_MIN_KERNEL_ADDRESS) /
-		    PAGE_SIZE / 4;
-
 	/*
 	 * Allocate a submap for exec arguments.  This map effectively limits
 	 * the number of processes exec'ing at any time.
diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index 322816d1090..19112eff659 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sysctl.c,v 1.169 2009/04/19 17:53:38 deraadt Exp $	*/
+/*	$OpenBSD: kern_sysctl.c,v 1.170 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $	*/
 
 /*-
@@ -535,6 +535,23 @@ kern_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
 	case KERN_CPTIME2:
 		return (sysctl_cptime2(name + 1, namelen -1, oldp, oldlenp,
 		    newp, newlen));
+	case KERN_CACHEPCT: {
+		int opct, pgs;
+		opct = bufcachepercent;
+		error = sysctl_int(oldp, oldlenp, newp, newlen,
+		    &bufcachepercent);
+		if (error)
+			return(error);
+		if (bufcachepercent > 90 || bufcachepercent < 5) {
+			bufcachepercent = opct;
+			return (EINVAL);
+		}
+		if (bufcachepercent != opct) {
+			pgs = bufcachepercent * physmem / 100;
+			bufadjust(pgs);
+		}
+		return(0);
+	}
 	default:
 		return (EOPNOTSUPP);
 	}
diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 6706e7262a9..c106a1a1b36 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_bio.c,v 1.113 2009/06/03 04:30:57 beck Exp $	*/
+/*	$OpenBSD: vfs_bio.c,v 1.114 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: vfs_bio.c,v 1.44 1996/06/11 11:15:36 pk Exp $	*/
 
 /*-
@@ -235,6 +235,33 @@ bufinit(void)
 	maxcleanpages = locleanpages;
 }
 
+/*
+ * Change cachepct
+ */
+void
+bufadjust(int newbufpages)
+{
+	/*
+	 * XXX - note, bufkvm was allocated once, based on 10% of physmem
+	 * see above.
+	 */
+
+	bufpages = newbufpages;
+
+	hidirtypages = (bufpages / 4) * 3;
+	lodirtypages = bufpages / 2;
+
+	/*
+	 * When we hit 95% of pages being clean, we bring them down to
+	 * 90% to have some slack.
+	 */
+	hicleanpages = bufpages - (bufpages / 20);
+	locleanpages = bufpages - (bufpages / 10);
+
+	maxcleanpages = locleanpages;
+}
+
+
 struct buf *
 bio_doread(struct vnode *vp, daddr64_t blkno, int size, int async)
 {
diff --git a/sys/sys/mount.h b/sys/sys/mount.h
index 0d515480cb6..5796fda878f 100644
--- a/sys/sys/mount.h
+++ b/sys/sys/mount.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mount.h,v 1.92 2009/06/03 14:45:55 jj Exp $	*/
+/*	$OpenBSD: mount.h,v 1.93 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: mount.h,v 1.48 1996/02/18 11:55:47 fvdl Exp $	*/
 
 /*
@@ -506,6 +506,8 @@ struct bcachestats {
 #ifdef _KERNEL
 extern struct bcachestats bcstats;
 #define BUFPAGES_DEFICIT (bufpages - bcstats.numbufpages)
+extern int bufcachepercent;
+extern void bufadjust(int);
 #endif
 
 /*
diff --git a/sys/sys/sysctl.h b/sys/sys/sysctl.h
index 19524fe8de0..21dde2bbf58 100644
--- a/sys/sys/sysctl.h
+++ b/sys/sys/sysctl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sysctl.h,v 1.96 2009/04/19 17:53:39 deraadt Exp $	*/
+/*	$OpenBSD: sysctl.h,v 1.97 2009/06/03 21:30:20 beck Exp $	*/
 /*	$NetBSD: sysctl.h,v 1.16 1996/04/09 20:55:36 cgd Exp $	*/
 
 /*
@@ -184,7 +184,8 @@ struct ctlname {
 #define	KERN_TIMECOUNTER	69	/* node: timecounter */
 #define	KERN_MAXLOCKSPERUID	70	/* int: locks per uid */
 #define	KERN_CPTIME2		71	/* array: cp_time2 */
-#define	KERN_MAXID		72	/* number of valid kern ids */
+#define	KERN_CACHEPCT		72	/* buffer cache % of physmem */
+#define	KERN_MAXID		73	/* number of valid kern ids */
 
 #define	CTL_KERN_NAMES { \
 	{ 0, 0 }, \
@@ -259,6 +260,7 @@ struct ctlname {
  	{ "timecounter", CTLTYPE_NODE }, \
  	{ "maxlocksperuid", CTLTYPE_INT }, \
  	{ "cp_time2", CTLTYPE_STRUCT }, \
+ 	{ "bufcachepercent", CTLTYPE_INT }, \
 }
 
 /*